Proximity sensor devices (also commonly called touch pads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, which uses capacitive, resistive, inductive, optical, acoustic and/or other technology to determine the presence, location and/or motion of one or more fingers, styli, and/or other objects. The proximity sensor device, together with finger(s) and/or other object(s), can be used to provide an input to the electronic system. For example, proximity sensor devices are used as input devices for larger computing systems, such as those found integral within notebook computers or peripheral to desktop computers. Proximity sensor devices are also used in smaller systems, including: handheld systems such as personal digital assistants (PDAs), remote controls, communication systems such as wireless telephones and text messaging systems. Increasingly, proximity sensor devices are used in media systems, such as CD, DVD, MP3, video or other media recorders or players.
One common application for a proximity sensor device is as a touch screen. In a touch screen, the proximity sensor is combined with a display screen for displaying graphical and/or textual elements. Together, the proximity sensor and display screen function as a user interface. In these applications the proximity sensor device can function as a value adjustment device, cursor control device, selection device, scrolling device, graphics/character/handwriting input device, menu navigation device, gaming input device, button input device, keyboard and/or other input device.
One issue with some past proximity sensor devices in general, and touch screens in particular, is that they have been prone to accidental activation. Specifically, because of the low force needed to activate the proximity sensor, a simple brush of the sensor can inadvertently actuate a function on the sensor. In many cases, an inadvertent activation can be merely inconvenient. For example, when parameter such as volume is inadvertently adjusted it may be annoying to the user, but not overly worrisome. However, in other cases, the inadvertent activation can be more problematic. For example, when the inadvertent activation causes applications to be closed improperly, or data to be unintentionally discarded. In these cases, the inadvertent activation can cause serious inconvenience for users.
Thus, there exists a need for improvements in proximity sensor device usability that facilitates the use of touch screens as interface devices while avoiding inadvertent activation of specified functions.